Chemical Oxygen Demand Values Research Articles

Water quality monitoring and modeling for an urban storm drainage channel in Thane, India.

The absence of a sewer system and inadequate wastewater treatment plants results in a discharge of untreated wastewater to the urban drainage channels and pollutes receiving waters. Field visits were carried out to observe water quality parameters such as dissolved oxygen (DO), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) in an urban drainage system (Kolshet drain) in Thane City, Mumbai Metropolitan Region, India. Dye-tracing studies using rhodamine WT dye were used for computing the velocity, discharge, and dispersion coefficient of the drain. The data analysis shows that the BOD and COD values in the drain are higher than the permissible limits (30mg L-1 for BOD and 250mg L-1 for COD), which is not suitable for disposal to any receiving water body. Also, the DO was less than the permissible limit of a minimum of 3mg L-1 (for the survival of aquatic life). It is seen that the higher BOD load significantly reduced the DO throughout the drain. The Water Quality Analysis Simulation Program (WASP 8.32, 2019) developed by the US Environmental Protection Agency (USEPA) has been used for the simulation of the DO and BOD in the drainage channel. The model simulates an appropriate estimate of the expected variation of DO and BOD at points of interest. The modeling for the Kolshet drain is expected to enable better estimates of the wastewater parameters and the pollution transport in the drain for planning purposes.

Monitoring of university wastewater within the sewage system and its performance evaluation through integrated constructed wetlands.

Rapid increase in population and industrialization has not only improved the lifestyle but adversely affected the quality and availability of water leading to ample amount of wastewater generation. The major contribution towards wastewater production is from sewage. Regular monitoring and treatment of sewage water is necessary to conserve and enhance the quality of water. The present study focuses on monitoring of sewage water within the sewage system of a residential university. A total of 16 samples from different manholes were collected for physicochemical and heavy metals analysis and compared with final effluent collected from integrated constructed wetlands (ICWs) to assess its removal efficiency. The mean concentrations of influent and effluent were compared with national environmental quality standards (NEQS) for municipal discharge (pH6-9, COD 150mg/L, TSS 200mg/L and TDS 3500mg/L) and international agricultural reuse standards (IARS) (pH6-8, COD <150mg/L, TSS < 100mg/L) respectively. Among all physicochemical parameters, influent values for chemical oxygen demand (COD) (169.56-258.36) mg/L exceeded the limit of NEQS for discharge into inland waters, whereas for total suspended solids (TSS) the concentration exceeded for discharge into STP (406mg/L) and inland waters (202.33mg/L). However, effluent concentrations for all the parameters were found within the permissible limit set by IARS. The removal efficiency for different parameters such as phosphate- phosphorus (PO43-P), COD, TSS, total dissolved solids (TDS) and total kjeldahl nitrogen (TKN) were 52, 53, 54, 35, and 36%, respectively. Heavy metal concentrations were compared with WHO guidelines among which lead (Pb) in effluent and chromium (Cr) in influent exceeded the limit (Pb 0.01 and Cr 0.05mg/L). Interpolation results showed that zone 2 was highly contaminated in comparison to zone 1 & 3. Statistical analysis showed that correlation of physicochemical parameters and heavy metals was found significant (p < 0.05).

Fluid dynamics and energy efficiency of submerged combustion process for treating wastewater with high salinity and COD concentration

Focusing on submerged combustion technology for the treatment of high salinity and high chemical oxygen demand (COD) wastewater, this study explores the characteristics of gas-liquid two-phase flow and heat transfer during the submerged combustion process, employing both experimental and numerical simulation methods.Consequently, the impact of essential parameters on the efficacy of submerged combustion in treating wastewater was analyzed. The experimental results show that increasing the fuel flow rate and immersion depth is beneficial to improve the temperature rise rate and shorten the evaporation time. With the increase of the organic solution flow rate and the initial COD value of the organic solution, the COD removal rate decreased, and the effect of the organic solution flow rate on the COD removal efficiency was more obvious. The use of a flat orifice plate or tapered orifice plate immersed tube structure can improve the thermal efficiency by over 10%. However, it is not conducive to the stability of the pressure in the combustor, increasing the fluctuation of the liquid level. Compared with that of traditional single-effect evaporation crystallization, the energy consumption of the submerged combustion device is decreased, and the total operation cost is reduced by 22.5%.

Distinguishable photorecycling of PVDF nanocomposites membrane for reactive yellow 145 dye and real industrial wastewater treatment by different photocatalytic processes

This paper investigates the photocatalytic performance and recyclability of PVDF-MWCNTs-TiO2 nanocomposite membranes for the treatment of textile wastewater under sunlight irradiation. The nanocomposites were fabricated by incorporating varying weight ratios of MWCNTs-TiO2 (1 %, 3 %, 6 %, and 9 %) into PVDF matrices using a solvent casting method. Optimal loading of MWCNTs-TiO2 at 9 wt% resulted in nanocomposites with enhanced surface area (94.15 m2/g), reduced band gap (2.38 eV), uniform dispersion of nanoparticles, and abundant surface hydroxyl groups. Under Xenon lamp irradiation, the optimized PVDF-9 %(MWCNTs-9 %TiO2) nanocomposite achieved a high apparent reaction rate constant (kapp) of 9.92 × 10−3 s−1 for photocatalytic degradation of the model dye Reactive Yellow 145. Significantly, when tested on-site at a Saudi Arabian textile facility over 6 months, this nanocomposite effectively reduced the chemical oxygen demand (COD) of real wastewater samples to regulatory limits of 1000 ppm under natural sunlight irradiation. The COD values were lowered from an initial 5050–6200 ppm to a final range of 785–945 ppm using the PVDF-9 %(MWCNTs-9 %TiO2) membrane. Furthermore, the optimized nanocomposite exhibited good recyclability, retaining around 87 % of its initial activity after 8 reuse cycles for industrial wastewater treatment. The excellent photocatalytic efficiency and reusability of the MWCNTs-TiO2 modified PVDF nanocomposite under solar irradiation highlight its promise as a sustainable membrane technology for environmental remediation.

Assessing the water quality of River Ganga in Varanasi, India, through WQI, NPI, and multivariate techniques: a comprehensive study

Abstract The present research was conducted to study the water quality of the Ganga River in Varanasi. Water quality from nine different sampling points (S1–S9) from the River Ganga at Varanasi was examined for different water quality parameters, and multivariate statistical analyses were carried out. Subsequently, several indices, such as water quality index and Nemerow pollution index (NPI), were calculated. The results indicated that water in the Ganga River at Varanasi had high levels of coliform concentrations, altered pH, and elevated dissolved oxygen/biochemical oxygen demand and chemical oxygen demand values. The weighted arithmetic water quality index values revealed that sites S8, S9, and S2 were the most polluted and unfit for bathing and drinking. Most of the sampling sites have NPI values greater than 1 for several parameters, indicating high levels of pollution. The study revealed that the water quality is poor for bathing and drinking at most of the sites throughout the year. In addition, the upstream water quality assessment revealed that water quality was good compared with the heavily contaminated downstream region. This knowledge can be useful for environmentalists, policymakers, and water resource managers to develop strategic plans to preserve the cultural and aesthetic worth of the Ganga River in the future.

Electrochemical Oxidation Treatment of Organic Matter in Wastewater from Wet Fermentation of Yunnan Arabica Coffee

Electrochemical oxidation combined with reagents of O3, H2O2 and FeCl2 was conducted in this study to treat the wastewater from wet fermentation of Yunnan arabica coffee. In addition, the effect of oxidants on the efficiency of wastewater treatment, the binding capacities of the oxidants to proteins, the degradation of organic pollutants in the wastewater, and the formation of oxidized organic components were systematically investigated. The results reveal better performance of O3-combined electrochemical oxidation (63.60% COD removal efficiency) for treatment of organic species in coffee wastewater than that of the electrochemical processes with H2O2 (47.70% COD removal efficiency) and FeCl2 (34.48% COD removal efficiency). The synergy of the electrooxidation/O3 process (0.0133 A/cm2, 20 mg/L–2 L/min) could not only raise the pH value (3.70~4.20, 5.14~5.44) of the wastewater and reduce the NaOH dosage of 2.80~3.7 g/L, but also effectively degrade the proteins, lipids, unsaturated hydrocarbons, and carbohydrates, with a total chemical oxygen demand (COD) value above 20,000 mg/L. After the oxidation treatment, some organic components remained in the wastewater, including 31.94% of S-containing organics, lignin, condensed aromatic compounds, and aromatic structural compounds, which are difficult to be utilized by microorganisms. In addition, it was found that OH− could bind to proteins and affect the required amount of NaOH addition, whereas the protein binding energy of O3 is higher than that of H2O2, indicating a stronger ability of O3 to oxidize proteins. Therefore, the combination of O3 and electrochemical oxidation can be considered as an effective method to treat organic pollutants in the wastewater from wet fermentation of Yunnan arabica coffee.

Microbiological treatment of post-industrial water: Example of efficient bioremediation of the heavily polluted Kalina pond, Poland

The Kalina pond has been well known as a severely degraded area in the Silesia region, Poland. The environmental deterioration results from high contamination of water and bottom sediments with recalcitrant and toxic organic compounds, mainly phenol. The study was aimed at developing a bioremediation-based approach suitable for this type of polluted areas, involving microbiological treatment of water as a key and integral part of other necessary actions: mechanical interventions and the use of physical methods. During the initial biological treatment stage, autochthonous microorganisms were isolated from contaminated samples of water, soil and sediment, then subjected to strong selective pressure by incubation with the pollutants, and finally, cultivated to form a specialised microbial consortium consisting of five extremophilic bacterial strains. Consortium propagation and its biodegradation activity were optimised under variant conditions enabling bacteria to proliferate and to obtain high biomass density at large volumes allowing for the in situ application. After installing aeration systems in the pond, the consortium was surface-sprinkled to launch bioremediation and then both bacterial frequency and the contaminant level was systematically monitored. The complex remediation strategy proved efficient and was implemented on an industrial scale enabling successful remedial of the affected site. Treatment with the specifically targeted and adapted microbial consortium allowed for removal of most organic pollutants within a four-month season of 2022: the chemical oxygen demand (COD) value decreased by 72%, polyaromatic hydrocarbon (PAH) level by 97%, while the content of total phenols and other monoaromatic hydrocarbons (BTEX) dropped below the detection thresholds.

Smart water: An innovative approach to integrated water management at the Faculty of Sciences Ben M’sick (Casablanca, Morocco) in the face of water stress

The integrated management of water resources at the level of various human activities is today imperative for individuals and organizations. This study investigates the possibilities of applying a responsible and sustainable water management approach at the Ben M’sik Faculty of Sciences (FSBM) in Casablanca through rainwater collection/reclamation, groundwater exploitation and decentralized treatment/internal wastewater reuse. To this end, physicochemical characterization of these three types of water was carried out, with preliminary results showing that the wastewater quality complied with the discharge limits recommended by Lydec for all the parameters determined, except for Chemical Oxygen Demand (COD) and Total suspended solids (TSS), with average values for COD, BOD5, and TSS of around 1010.12 mg L -1, 87.27 mg L-1 and 370.48 mg L-1 respectively. In parallel, average values for COD/BOD5 (33.19), TSS/BOD5 (6.03) and oxidizable matter (360.72 mg L-1) revealed that these wastewaters are heterogeneous and poorly biodegradable. As for rainwater and groundwater, the results show that they comply with the quality grid for water intended for irrigation, except for chloride (715.23 to 884.72 mg L-1) and nitrate for groundwater (61.45).

Research and Development of the Treatment Effectiveness of a Novel Process for Vegetable Biogas Slurry Purification

Nowadays, an anaerobic filter is used in treating various wastewaters that is more effective for denitrification and organic removal. The Anaerobic Filter with Inoculum, Soft and Hard Packing Medium (AFISH) and Double-Filling Aerobic Baffle (DFAB) reactors were continuously operated for 120 days with a short Hydraulic Retention Time (HRT) in the range of 1 and 2 days at an Organic Loading Rate (OLR) of 0.58 and 1.08 gCOD/(l.d) by daily feeding the influent Chemical Oxygen Demand (COD) concentration between 1169 and 250 mg/l. After treating the sample wastewater in the new AFISH reactor, the effluent flowed into the DFAB reactor for further treatment to determine the treatment effectiveness of the novel AFISH and DFAB reactors at a short HRT of 1 to 2 days. The influent COD was reduced to 376 mg/l to 250 mg/l in a novel AFISH effluent and further dropped to 220 mg/l to 102 mg/l following DFAB reactor treatment. The COD removal in the AFISH reactor was around 67% when HRT was about 1 day, and a high COD value of 78% was removed during the HRT of 2 days, while in the DFAB reactor, the capability of treatment reached between 40% and 57% of the COD removed at the HRT of 1 and 2 days. The concentration of NH4-N in the effluent of the novel AFISH reactor was significantly lower than the effluent of the DFAB reactor, with NH4-N concentrations ranging from 157 mg/l to 330 mg/l. However, the treatment of vegetable bio-slurry from the Internal Circulation (IC) reactor by the novel AFISH and DFAB reactors satisfied the secondary wastewater discharge standard in the Integrated Wastewater Discharge Standard. Therefore, this novel process is one method beneficial for current and further research development that can be applied for industrial wastewater treatment processing and provides science information to those interested in research in the future.

Integrated control strategy for dual sludge ages in the high-concentration powder carrier bio-fluidized bed (HPB) technology: Enhancing municipal wastewater treatment efficiency

The high-concentration powder carrier bio-fluidized bed (HPB) technology is an emerging approach that enables on-site upgrading of wastewater treatment plants (WWTPs). HPB technology promotes the formation of biofilm sludge with micron-scale composite powder carriers as the core and suspended sludge mainly composed of flocs surrounding the biofilm sludge. This study proposed a novel integrated strategy for assessing and controlling the sludge ages in suspended/bio-film activated sludge supported by micron-scale composite powder carrier. Utilizing the cyclone unit and the corresponding theoretical model, the proposed strategy effectively addresses the sludge ages contradiction between denitrifying bacteria and polyphosphate-accumulating organisms (PAOs), thereby enhancing the efficiency of municipal wastewater treatment. The sludge age of the suspended (25 d) and bio-film (99 d) sludge, calculated using the model, contribute to the simultaneous removal of nitrogen and phosphorus. Meanwhile, the model further estimates distinct contributions of suspended and bio-film sludge to chemical oxygen demand (COD) and total nitrogen (TN), which are 55% and 42% for COD, 20% and 57% for TN of suspended sludge and bio-film sludge, respectively. This suggests that the contribution of suspended sludge and bio-film sludge to COD and TN removal efficiency can be determined and controlled by the operational conditions of the cyclone unit. Additionally, the simulation values for COD, ammonia nitrogen (NH4+-N), TN and total phosphorus (TP) closely align with the actual values of WWTPs over 70 days (p < 0.001) with the correlation coefficients (R2) of 0.9809, 0.9932, 0.9825, and 0.837, respectively. These results support the theoretical foundation of HPB technology for simultaneous nitrogen and phosphorus removal in sewage treatment plants. Therefore, this model serves as a valuable tool to guide the operation, design, and carrier addition in HPB technology implementation.

Valorising Desizing Textile Effluent

Textile wet processing is an energy-intensive and water-consuming process. Right from pretreatment to finishing several basic, auxiliary, and specialty chemicals are used during the manufacturing of textiles. There are two main processes, namely sizing and desizing which are mutually responsible for increasing the Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) values of liquid effluent emerging after the pretreatment process. This review describes in detail the types of commercial sizing agents depending on their origin, performance, and environmental profile. The review further throws light on the possibilities of extracting energy-efficient, value-added products from the residual waste and effluent. Such recovery mechanisms can enhance sustainability and bring circularity to textile wet processing.

Switchable superlyophobic PAN@Co-MOF membrane for on-demand emulsion separation and efficient soluble dye degradation

Developing membrane surfaces with double superlyophobicity properties under liquids for different separation applications poses significant challenges in thermodynamics and material science. Switchable superwettability is usually achieved through complex manipulation means and the application of external stimuli such as light, heat, electrical current, and so on. In this study, a reversible superhydrophobic/superoleophobic membrane (PAN@Co-MOF) was fabricated conveniently by in situ growth of Co(Hmim)2 (Co-MOFs) onto the surfaces of electrospun polyacrylonitrile (PAN). The as-prepared PAN@Co-MOF membrane facilitated the selective passage of water or oil in a unidirectional manner, only when water or oil was prewetted, which enabled the efficient separation of oil-in-water (O/W) or water-in-oil (W/O) emulsions on demand. This novel organic and inorganic hybrid material overcame traditional limitations, resulting in a mechanically robust and reusable membrane. Moreover, the PAN@Co-MOF membrane demonstrated the capability to activate peroxymonosulfate (PMS) for efficient dye degradation through interactions of Co-MOF with diverse liquids. Impressively, the O/W emulsion separation flux surpassed 1600 L·m−2·h−1 with chemical oxygen demand (COD) values of the filtrate below 100 mg·L−1, while the W/O emulsion separation flux exceeded 1040 L·m−2·h−1, maintaining the water content of the filtrate under 50 mg·L−1. Furthermore, the degradation efficiency of methylene blue (MB) (50 ppm) achieved a staggering 99.3% within 10 min. This study offers an innovative idea for the development of multifunctional membrane materials with switchable superwettability in the integrated oil–water treatment.

Progressive pollution abatement in raw dairy wastewater induced by the algae Poterioochromonas malhamensis with a high-value biomass yield

This work aimed to systematically abate in batch mode organic pollutants from raw dairy wastewater (DW) with high values of chemical oxygen demand (COD, ∼10.3 g L−1), total organic carbon (TOC, ∼2.4 g L−1), and total nitrogen (TN, ∼0.28 g L−1) by using the Poterioochromonas malhamensis algae strains. In this regard, variables such as fractions of DW (40–100%, v/v), mineral nutritional inoculum addition (0–100%, w/v) and CO2-enriched air (2–8%) were proposed to address a study in optimizing conditions with new insights on algae production. As controlled photobioreactors (PBR), a set of tubular PBRs and a pair of flat-plate PBRs (FP-PBR) surrounded by fluorescent lamps and pumped by CO2-enriched air at a flow rate of 1.4 L min− 1 per litre were used. A Box-Behnken design (BBD) for algal growing was applied using the set of tubular PBRs to get a better reduction in TOC, TN and COD, defining an optimized condition. On the best tubular PBRs-based outcome and including a holed baffles system for hydrodynamically providing a flashing light state, 9-day kinetic experiments based on a pair of FP-PBRs were performed to provide more insights on how to enhance the algal yield and COD, TN and TOC reduction. A biomass yield rate of 1.1 g L−1 per day was attained using FP-PBRs, being comparatively 10% better than tubular PBRs. Additionally, the organic pollution abatement in DW was highly significant, with a decrease of about 98%, 95%, and 92% in COD, TN and TOC, respectively, besides changing the initial bacteria diversity to another less harmful one.

Influence of Cotton Bleaching Methods on the Parameters of Generated Textile Industrial Wastewater

The environmental impact of industrial wastewater after bleaching requires special attention to prevent the pollution of aquatic ecosystems. The aim of this study was to compare the effluent parameters obtained after using a traditional bleaching method and an alternative enzymatic bleaching method in order to assess their possible environmental impacts. In the classical bleaching method, NaOH and H2O2 were used, and in the alternative method, pectinase enzyme, H2O2, and sodium carbonate were used as the bleaching agents. The bleaching process was designed by determining the optimum amount of pectinase enzyme, the optimum temperature, and the optimum amount of peroxide. The whiteness of the treated cotton yarns was also evaluated. The different bleaching processes were analyzed and evaluated in terms of the wastewater discharged, the pH, chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), and conductivity. These data show that the use of the pectinase enzyme allows us to obtain much lower COD and TSS values compared to those obtained using traditional bleaching. At the same time, the use of the proposed enzymatic bleaching method reduces the environmental impact since lower concentrations of pollutants are obtained in the effluent. Therefore, the pretreatment of wastewater may require the selection of a simpler and more environmentally friendly technology, such as enzymatic bleaching.

Physicochemical and biological characteristics of River Hindon at Galheta station from 2009 to 2020

AbstractThis study aimed to assess the physicochemical and biological attributes of water in the Hindon River, located in Northern India and traversing through the districts of Saharanpur, Muzaffarnagar, Meerut, Baghpat, Ghaziabad, and Gautam Buddha Nagar. The study specifically examined crucial parameters, including Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Alkalinity (TA), Sulphate (SO42−), Total Dissolved Solids (TDS), and the biological parameter, that is, Total Coliform. Data for these characteristics of the Hindon River were collected and analyzed based on measurements obtained at the Galheta station in District Baghpat, from 2009 to 2020. The study revealed significant yearly fluctuations in water quality parameters. DO (0.15–9 mg/L) and Total Coliform (319.09 MPN/100 mL to 23 × 106 MPN/100 mL) levels represented the most significant variations, while BOD (30.65–81.54 mg/L) and COD (80.08–170 mg/L) values consistently exceeded acceptable thresholds. TA (151.883–444.86 mg/L) had persistently fallen short of minimum standards, whereas SO42− (24.756–77.441 mg/L) remained within permissible limits. TDS (619–924.16 mg/L) consistently adhered to water quality standards. The findings indicated that the Hindon River's water quality consistently fell into the categories D or E as per Bureau of Indian Standards (IS: 2296) and Class III or IV according to the UNECE (United Nations Economic Commission for Europe) standards and failed to meet the stipulated criteria outlined in BIS (IS: 2490) and had fallen short of the water quality standards established by the World Health Organization (WHO). A correlation coefficient matrix was generated to assess the relationships among the mentioned parameters. The research findings emphasize the need for continuous monitoring of Hindon River water to protect the health of aquatic ecosystems and human well‐being.

Absorbent mixtures optimisation for COD and Ammonia Nitrogen reduction in stabilised leachate

This paper describes the optimisation of mixed media for Chemical Oxygen Demand (COD) and Ammonia Nitrogen (NH3-N) removal from stabilised leachate by feldspar (FE), zeolite (ZE), activated carbon (AC), and cockle shells (CS) mixtures using D-optimal mixture design. Linear equations characterised the optimal mixture. The optimum mitigation of COD and NH3-N in landfill leachate was favourable at 12.5 mg/L, 9.72 mg/L, 6 mg/L, and 11.79 mg/L of adsorbent mixed dosage for FE, ZE, AC, and CS, respectively, with the desirability value of 0.886. The predicted R-squared values for NH3-N (0.9839) and COD (0.8972) were in close agreement with the adjusted R-squared values of 0.9940 and 0.9900 for COD and NH3-N, respectively, which validates the obtained regression models. The Lack of Fit F-values of 0.6015 (COD) and 0.4565 (NH3-N) are insignificant, indicating that the models accurately predict the removal. The Fourier transform infrared spectroscopy (FTIR) revealed that the predominant hydroxyl group consisted of –OH at spectra 3306.18 and 3338.74. The study also revealed that the D-optimal mixture design has extremely high application potential as it produces a good mixture design based on the remediation of contaminants from stabilised leachate.

Vertical flow wetlands as the core for the sustainable treatment of coffee wastewater in small communities in Colombia: preliminary results of the treatment of coffee wastewater in rural areas by vertical flow wetlands.

Coffee is one of the most important agricultural products in Colombia. To date, small-scale Colombian coffee growers have developed this activity with a simple infrastructure and random use of water that generates harmful by-products to the water resource mainly in the stage of separation of the mucilage. The coffee mucilage wastewater (CMW) is composed of high organic loads and its impact on water sources is due to its high load of nutrients such as nitrogen (N), phosphorus (P), and chemical oxygen demand (COD) values of over 25,000 mg/L. However, there is no consensus on what treatment can be used, especially whether it is accessible to coffee producers. Thus , the aim of this study consisted of assessing the performance of the combination of a carbon filter (CF) as pretreatment and vertical flow wetland (VFW) as a Natural-based Solution (NbS). The results show a reduction of more than 85% of COD, 96% of total solids, and UV254 close to 94%. It was remarkable that both treatments are appropriate for waters with a high concentration of solids. Finally, it can be concluded that CF + VFW is a feasible technology to treat the coffee wastewater from small communities of coffee producers.

Modelling of a wastewater-treatment plant for process reliability and effluent reuse

Evaluation of wastewater-treatment plant (WWTP) performance is important to determine whether the plant produces an acceptable treated effluent satisfying the water quality standards for reuse. Modelling of WWTPs is required for optimising plant performance and choosing the optimum operation strategy. This study simulated the Kabd WWTP in Kuwait using the BioWin software. The plant receives 180 000 m3/day of domestic wastewater and comprises primary, secondary (activated sludge) and tertiary treatment stages. Daily data obtained from the WWTP during 2013–2018 were used for modelling plant performance under steady-state operation. The model could describe plant operation and accurately predict the effluent characteristics for the conditions examined. A high correlation (R 2 = 0.95–0.99) was obtained between the predicted and actual values of chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids as main parameters characterising wastewater. The tertiary-treated effluent consistently satisfied the water quality criteria for reuse in irrigation. Using the model could aid in securing compliance of effluent quality with the local environmental standards. Factorial analysis revealed that COD and BOD are the most important parameters describing plant performance. Reliability analysis showed that the coefficient of variability was low (0.328) at a level of reliability of 95%, leading to a high coefficient reliability of 0.631, which indicates a highly stable plant performance. It is recommended to include reliability analysis in evaluating plant performance to demonstrate consistency in the ability of the plant to produce effluents satisfying requirements set by environmental authorities.

Single-wavelength colorimetric tests for low-cost estimation of bacterial activity, chemical oxygen demand, and turbidity in domestic wastewater

Abstract Monitoring the characteristics of wastewater can enable a better choice of the options available for its treatment and also provide a rational basis for the surveillance of the spread of waterborne diseases. Our work focused on bringing down the costs associated with the estimation of the biological and physico-chemical parameters of wastewater at a common wavelength of 600 nm. We demonstrated the advantages of using the Dye Reduction-based Electron-transfer Activity Monitoring (DREAM) assay to estimate bacterial activity as an alternative to the bacterial colony count method. This assay relies on the colorimetric measurement of the extent of reduction of methylene blue in response to bacterial electron transfer. We also present the results of estimating COD and turbidity, using the standard methods of wastewater analysis, at the same wavelength of 600 nm using samples having known values of chemical oxygen demand (COD) and turbidity. Our results open up the possibility of replacing expensive spectrophotometers with LED-based, microcontroller enabled colorimeters that can be easily automated. The results of our study set the stage for the establishment of a greater number of wastewater analysis laboratories in economically backward regions which can in turn support measures to improve sanitation facilities.

Physical, chemical, and biological evaluation of domestic laundry greywater discharges to attract reclamation strategies and reuse applications in urban settings

AbstractDue to increasing freshwater demand and limited availability of resources, conservation and recycling of greywater are getting attention worldwide. Greywater (GW) is considered a potential contender to different types of industrial wastewater in terms of recyclability, toxicity, and reusability. The reuse and treatment methodologies in the case of LGW mainly depend on parameters such as pH, Biochemical oxygen demand (BOD), Chemical oxygen demand (COD), Total dissolved solids (TDS), Total suspended solids (TSS), turbidity, ionic concentration, surfactants, and microbial growth. Available literature suggests that domestic as well as commercial laundries are major contributors to greywater around the globe. This paper presents the results of investigations conducted on the quantity and quality of greywater generated from domestic urban laundries. Various factors were observed that influence the quantity of generated LGW such as family size, type of washing (machine or manual), and composition of LGW influenced by the work profile of family members, etc. The average values of BOD, COD, TSS, TDS, turbidity, Chloride (Cl−), Sulphate (SO42−), Fluoride (F−), Nitrate (NO3−), and anionic surfactants as MBAS (methylene blue active substances) were observed as 265.73 mgL−1, 1754.67 mgL−1, 469.13 mgL−1, 1837.73 mgL−1, 281.8 NTU, 438.6 mgL−1, 87.93 mgL−1, 0.87 mgL−1, 6.83 mgL−1, and 16.45 mgL−1, respectively. The average concentration of Escherichia coli and total coliforms was observed to be 73.4 MPN/100 mL (most probable number per 100 mL) and 386.2 MPN/100 mL, respectively. The high values of selected parameters necessitate the planning of greywater treatment in urban locations for re‐utilization. This study also revealed that a huge amount of freshwater is being converted to greywater by domestic laundries that can be re‐utilized for non‐potable purposes after some treatment.